Good evening Miles and welcome back!
Thank you for reaching out to us.
We are sorry to hear about the struggles you have been dealing with while installing your license.
I would love to help you with this topic.
The good news is that you can totally move your licenses around.
As a result, I would recommend:
- Reading the following: https://theeventscalendar.com/knowledgebase/moving-your-license-keys/
- Disconnecting and reconnecting your license.
If that still does not work, it might be because you need to install the plugin at a local install level and not at the multi-site level : https://theeventscalendar.com/knowledgebase/multisite-license/
Let me know if that helps.
Have a great day!
Geoff B.